Hammertoe implant and instrument

ABSTRACT

A bone implant comprising an elongate body having a first end and a second end coupled by a shaft is disclosed. The first portion is configured to couple to a first bone. The second portion comprises a first expandable section comprising at least one expandable feature. The first expandable section is configured to be received within a reverse countersink in a second bone in a collapsed state and to expand within the reverse countersink. The expandable feature couples to a bearing surface of the reverse countersink. A surgical tool comprising a shaft and at least one expandable cutting edge is disclosed. The shaft is sized and configured to be received within a canal formed in a bone. The expandable cutting edge is formed integrally with the shaft. The expandable cutting edge is configured to expand from a collapsed position to an expanded position for forming a reverse countersink.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/403,746 filed Nov. 25, 2014, which is a national phase entry under 35U.S.C. § 371 of International Patent Application No. PCT/US2014/056315,filed Sep. 18, 2014, the entireties of which are incorporated herein byreference.

FIELD OF THE INVENTION

This disclosure generally relates to systems and methods for orthopedicsurgery. More particularly, this disclosure relates to systems andmethods for hammertoe implants.

BACKGROUND

A hammertoe, or contracted toe, is a deformity of the proximalinter-phalangeal joint of the second, third, or fourth toe causing thetoe to be permanently bent and giving the toe a semblance of a hammer.Initially, hammertoes are flexible and may be corrected with simplemeasures but, if left untreated, hammertoes may require surgicalintervention for correction. Persons with hammertoe may also have cornsor calluses on the top of the middle joint of the toe or on the tip ofthe toe and may feel pain in their toes or feet while having difficultyfinding comfortable shoes.

One method of treatment may include correction by surgery if othernon-invasive treatment options fail. Conventional surgery usuallyinvolves inserting screws, wires or other similar implants in toes tostraighten them. Traditional surgical methods generally include the useof Kirschner wires (K-wires). K-wires require pings protruding throughthe end of respective toes due to their temporary nature. As a result,K-wires often lead to pin tract infections, loss of fixation, and otherconditions. Additional disadvantages of K-wires include migration andbreakage of the K-wires thus resulting in multiple surgeries. Due to thevarious disadvantages of using K-wires, however, compression screws arebeing employed as an implant alternative.

Screw implants may provide a more permanent solution than K-wires assuch implants do not need removal and have no protruding ends. Further,with the use of screw implants, a patient may wear normal footwearshortly after the respective surgery. There are generally two types ofknown screw implants: single-unit implants, which possess a completelythreaded body and do not provide a flexibility to the respective toe inits movement, and articulated or two-unit implants, which typically haveone unit that is anchored into the proximal phalanx, a second unit thatis anchored into the distal phalanx, and a fitting by which the twounits are coupled. Either or both of the two units may be threaded orhave other anchoring structures such as barbs or splaying arms.

Among other disadvantages, both kinds of known implants result in anundesirable pistoning effect, i.e., part or all of the implant willtoggle or move within the bone as the patient's toe moves. Pistoningdecreases the stability of the implant and lessens the compressionacross the joint. Moving parts, such as fittings, hinges, expansionpieces, and the like also decrease the stability, lifespan, andcompression force of the implant. Accordingly, there remains a need fordurable hammertoe implants which are not only stable but provideadequate compression across a joint with minimal pistoning. There alsoremains a need for an implant which can provide these advantages, whilebeing easily inserted with minimal damage to the surrounding tissue.

SUMMARY

The present subject matter relates to a type of bone implant useful inthe correction of hammertoe and similar maladies, as well as methods ofinserting the implant into bones to effectuate that correction. The boneimplant has a number of different embodiments, each of which correspondto different nuances in their respective methods of insertion. All ofthe hammertoe implant embodiments have an elongate shaft having a firstend and a second end coupled by a shaft. The first end is configured tocouple to a first bone. The second end comprises an expandable sectioncomprising at least one expandable feature. The expandable feature isconfigured to be received within a reverse countersink in a second bonein a collapsed state. The first expandable section expands within thereverse countersink such that the at least one expandable featurecouples to a bearing surface of the reverse countersink.

In some embodiments, a surgical tool is disclosed. The surgical toolcomprises a shaft sized and configured to be received within a canalformed in a bone. At least one expandable cutting edge is formedintegrally with the shaft. The expandable cutting edge is configured toexpand from a collapsed position for insertion into the canal to anexpanded position for forming a reverse countersink in the canal.

In some embodiments a method for correcting a hammertoe is disclosed.The method comprises the steps of forming a first canal in a first boneand forming a second canal in a second bone. A second step of the methodcomprises inserting a surgical instrument into the second canal. Thesurgical instrument comprises a shaft, a head located at a first end ofthe shaft, and an expandable cutting edge formed integrally with theshaft. The expandable cutting edge is deployable from a collapsedposition to a deployed position to forming a reverse countersink in thecanal. In a third step, the surgical instrument is rotated to form thereverse countersink in the second canal of the second bone.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention will be more fullydisclosed in, or rendered obvious by the following detailed descriptionof the preferred embodiments, which are to be considered together withthe accompanying drawings wherein like numbers refer to like parts andfurther wherein:

FIG. 1 illustrates one embodiment of a hammertoe implant comprising anexpandable section and a threaded section.

FIG. 2 is a side-view of the hammertoe implant of FIG. 1 having theexpandable section in a collapsed state.

FIG. 3 is a side-view of the hammertoe implant of FIG. 1 having theexpandable section in an expanded state.

FIG. 4 illustrates one embodiment of a cutting instrument having adeployable cutting section for forming a reverse countersink in a bone.

FIG. 5 illustrates the cutting instrument of FIG. 4 having thedeployable cutting section in a deployed position.

FIG. 6 illustrates one embodiment of the cutting instrument of FIG. 4inserted into a canal formed in a bone.

FIG. 7A illustrates one embodiment of the hammertoe implant of FIG. 1engaging a bone section in a collapsed state.

FIG. 7B illustrates the hammertoe implant of FIG. 7A engaging a bone inan expanded state.

FIG. 8A illustrates one embodiment of the hammertoe implant of FIG. 1engaging a bone section in a collapsed state.

FIG. 8B illustrates the hammertoe implant of FIG. 8A inserted into areverse countersink.

FIG. 9 illustrates an expanded view of a conical countersink having thehammertoe implant of FIG. 1 inserted therein.

FIG. 10 illustrates one embodiment of a hammertoe implant comprising anexpandable section having a first arm and a second arm.

FIG. 11 illustrates one embodiment of a hammertoe implant comprising acylindrical shaft section.

FIG. 12 illustrates one embodiment of a hammertoe implant having a firstexpandable section and a second expandable section.

FIG. 13 is a perspective view of the hammertoe implant of FIG. 12 in acollapsed state.

FIG. 14 is a perspective view of the hammertoe implant of FIG. 12 in anexpanded state.

FIG. 15 illustrates one embodiment of a hammertoe implant having a firstexpandable section, a second expandable section, and a cylindricalshaft.

FIG. 16 is a perspective view of the hammertoe implant of FIG. 15 in anexpanded state.

FIG. 17 illustrates the hammertoe implant of FIG. 15 inserted into afirst bone and a second bone.

FIG. 18 illustrates one embodiment of a combination sleeve and driverconfigured to insert the hammertoe implant of FIG. 1.

FIG. 19 illustrates one embodiment of a combination sleeve and driverconfigured to insert the hammertoe implant of FIG. 1.

FIG. 20 illustrates a method of treating a hammertoe using a hammertoeimplant.

FIG. 21 illustrates a method of treating a hammertoe using a hammertoeimplant.

DETAILED DESCRIPTION

The description of the exemplary embodiments is intended to be read inconnection with the accompanying drawings, which are to be consideredpart of the entire written description. In the description, relativeterms such as “lower,” “upper,” “horizontal,” “vertical,” “above,”“below,” “up,” “down,” “top” and “bottom,” as well as derivativesthereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should beconstrued to refer to the orientation as then described or as shown inthe drawing under discussion. These relative terms are for convenienceof description and do not require that the apparatus be constructed oroperated in a particular orientation. Terms concerning attachments,coupling and the like, such as “connected” and “interconnected,” referto a relationship wherein structures are secured or attached to oneanother either directly or indirectly through intervening structures, aswell as both movable or rigid attachments or relationships, unlessexpressly described otherwise.

The present disclosure generally provides a hammertoe implant andinstrument for joining a first bone and a second bone, such as, forexample, a proximal phalanx and a middle phalanx. The hammertoe implantgenerally comprises a first end and a second end coupled by a shaft. Thefirst end is configured to couple to the first bone. The second endcomprises an expandable section. The expandable section is configured tocouple the implant to the second bone. The expandable section expandsinto a reverse countersink formed in the second bone. The countersink isformed by an instrument generally comprising a shaft having anexpandable cutting member formed integrally therein. The expandablecutting member is deployable from a collapsed position to an expandedposition configured to form the reverse countersink in the bone.

FIG. 1 illustrates one embodiment of a hammertoe implant 2 comprising afirst end 4 and a second end 8 coupled by a shaft 6. The first end 4 isconfigured to anchor the hammertoe implant 2 to a first bone. Forexample, in some embodiments, the first end 4 comprises a threadedsection 12 configured to be received within a canal formed in a firstbone. The threaded section 12 may configured to be inserted into apre-drilled and/or pre-tapped canal and/or may comprise a self-drillingand/or self-tapping thread. The threaded section 12 may comprise apredetermined length configured to be fully implanted into the firstbone. In some embodiments, the first end 4 comprises other suitablemechanisms for coupling the hammertoe implant 2 to the first bone.

The second end 8 comprises an expandable section 10. The expandablesection 10 comprises one or more expandable features. For example, insome embodiments, the expandable section 10 comprises a plurality ofexpandable arms 10 a-10 d. In other embodiments, the expandable section10 may comprise, for example, one or more expandable cones, sleeves,threads, or any other suitable expandable feature. The expandablesection 10 is configured to transition from a collapsed position to anexpanded position. The expandable arms 10 a-10 d may be arranged in anysuitable configuration. For example, the expandable section 10 comprisesfour expandable arms 10 a-10 d arranged in a plus-sign configurationhaving a separation angle between each of the expandable arms 10 a-10 dof ninety degrees. It will be recognized that other configurations,including fewer or additional expandable arms and/or different angles ofseparation, are within the scope of the claims.

The first end 4 and the second end 8 are coupled by a shaft 6. The shaft6 may comprise any suitable cross-section, such as, for example, acylinder, square, triangle, and/or other suitable cross-section. Theshaft 6 comprises a predetermine length. The predetermined length of theshaft 6 may be configured to provide a predetermined spacing between thefirst bone and the second bone when the hammertoe implant 2 is inserted.In some embodiments, the shaft 6 comprises a predetermined length suchthat there is substantially no space between the first bone and thesecond bone after insertion of the hammertoe implant 2.

The hammertoe implant 2 is configured to couple the first bone to thesecond bone. In some embodiments, the threaded section 12 is insertedinto the first bone by rotating the threaded section 12 into contactwith the predrilled canal formed in the first bone. The expandablesection 10 is received within a cavity in the second bone. The cavity inthe second bone comprises a reverse countersink. The expandable arms 10a-10 d are configured to couple to a bearing surface of the reversecountersink and maintain the hammertoe implant 2 in the second bone. Insome embodiments, the hammertoe implant 2 is configured to join a middlephalanx and a proximal phalanx.

The hammertoe implant 2 may comprise any suitable material orcombination of materials. For example, in some embodiments, thehammertoe implant 2 may comprise Nitinol (in either the super-elastic orshape memory state), a Titanium alloy, stainless steel, an equivalentbio-material, and/or any combination thereof. In some embodiments, oneor more sections of the hammertoe implant 2, such as the expandablesection 10, comprises a first material, for example Nitinol, and asecond section of the hammertoe implant 2, such as the threaded section12, comprises a second material, for example, stainless steel.

FIG. 2 illustrates a side-view of the hammertoe implant 2 of FIG. 1having the expandable section 10 in a collapsed state. In the collapsedstate, the expandable arms 10 a-10 d are compressed to a first diameter.When the expandable arms 10 a-10 d are collapsed, the expandable end 10is sized and configured to be inserted through a canal formed in thesecond bone. The canal may comprise an internal diameter substantiallyequal to the first diameter of the expandable section 10. In someembodiments, a sleeve (see FIG. 18) is disposed over the expandable end10 to maintain the expandable arms 10 a-10 d in a collapsed state priorto insertion of the expandable section 10 in the second bone. Theexpandable arms 10 a-10 d may be maintained in a collapsed state, forexample, during insertion of the first end 4 into the first bone.

FIG. 3 illustrates a side-view of the hammertoe implant 2 of FIG. 1having the expandable section 10 in an expanded, or deployed, state. Inthe deployed state, the expandable arms 10 a-10 d are allowed to flare,or expand, out to a second diameter. The second diameter is greater thanthe diameter of the canal in the second bone. The expandable arms 10a-10 d may be biased to an expanded position. In some embodiments, thesecond diameter is greater than or equal to a diameter of a reversecountersink formed in the second bone. In the expanded state, theexpandable arms 10 a-10 d interface with a bearing surface of thereverse countersink.

In some embodiments, the reverse countersink in the second bone isformed by an instrument prior to insertion of the hammertoe implant 2into the second bone. FIGS. 4 and 5 illustrate one embodiment of aninstrument 50 configured to form a reverse countersink in the secondbone. The instrument 50 comprises an instrument tip 52 coupled to ashaft 54. The shaft 54 has a cutting edge 56 formed integrallytherewith. The cutting edge 56 is deployable from a collapsed state (asshown in FIG. 4) to a deployed state (as shown in FIG. 5). The cuttingedge 56 may comprise any suitable deployment mechanism such as, forexample, a mechanical deployment mechanism, a hinged deploymentmechanism, and/or any other suitable deployment mechanism. The shaft 54comprises a cavity 58 configured to receive the cutting edge 56 suchthat the cutting edge 56 is flush with the shaft 54 in a collapsedposition. In some embodiments, one or more additional cutting edges 56may be formed integrally with the shaft 54 and deployed simultaneously.In some embodiments, the diameter of the shaft 54 of the instrument 50is substantially equal to the diameter of the expandable section 10 ofthe hammertoe implant 2 in a collapsed position. The cutting edge 56 isconfigured to form a reverse countersink having a diameter that issubstantially equal to or less than a diameter of the expandable section10 of the hammertoe implant 2 in a deployed position. The reversecountersink provides a bearing surface for the expandable section 10 ofthe hammertoe implant 2.

FIG. 6 illustrates one embodiment of a second bone 62 having the cuttinginstrument of FIG. 4 inserted therein. The instrument 50 is insertedinto a canal 65 formed in the second bone 62 to a first predetermineddepth. The instrument tip 52 and the shaft 54 position the cutting edge56 at a second predetermined depth in the second bone 62. The cuttingedge 56 is deployed from a collapsed position (shown in FIG. 4) suitablefor insertion through the canal to a deployed position (shown in FIG.5). The instrument 50 is rotated about a central axis, causing thecutting edge 56 to form a reverse countersink 66 in the second bone 62.The cutting edge 56 may transition from a partially deployed position toa fully deployed position as bone is removed by the cutting edge 56during rotation of the instrument 50. Although the cutting edge 56 isconfigured to form a conical reverse countersink 66, it will beappreciated that the cutting edge 56 may be configured to form anysuitable cavity, such as, for example, a conical, square, or cylindricalcountersink. After forming the reverse countersink 66, the cutting edge56 is transitioned from the deployed position to the collapsed positionand the instrument 50 is removed from the canal 65.

FIG. 7A illustrates the hammertoe implant 2 anchored to the first bone60 and partially inserted into the second bone 62. The first end 4 ofthe hammertoe implant 2 is coupled to the first bone 60 by the threadedsection 12. The threaded section 12 is inserted into a canal 68 formedin the first bone 60. The canal 68 may be predrilled in the first bone60 by, for example, a drill, k-wire, and/or other suitable device and/ormay be formed by the hammertoe implant 2 during insertion of thethreaded section 12. The threaded section 12 extends within the firstbone 60 to a predetermined depth. In some embodiments, the threadedsection 12 may extend substantially the entire width of the first bone60. In some embodiments, the threaded section 12 is inserted to a depthsuch that a portion of the shaft 6 is located within the canal 68. Theexpandable section 10 is maintained in a collapsed position duringinsertion of the first end 4 into the first bone 60. The expandablesection 10 may be maintained in the collapsed position by, for example,a sleeve (see FIG. 18) disposed over the expandable section 10.

After coupling the hammertoe implant 2 to the first bone 60, the secondend 8 of the hammertoe implant 2 is inserted into the second bone 62.The expandable section 10 is inserted into a canal 65 formed in thesecond bone 62. The canal 65 applies a force to the expandable section10 that maintains the expandable arms 10 a-10 d in a collapsed positionduring insertion and allows the expandable section 10 to traverse thecanal 65. A gap exists between the first bone 60 and the second bone 62as the hammertoe implant 2 has not been fully inserted into the bone 62.

A first length, ‘A’, illustrates the distance of travel of theexpandable end 10 from the initial position illustrated in FIG. 7Abearing surface of the reverse countersink. A second length, ‘B’,illustrates the corresponding gap between the first bone 60 and thesecond bone 62. Having a distance ‘A’ substantially equal to the length‘B’ ensures the joint fully closes when the implant 2 is inserted. Asshown in FIG. 7B, when the hammertoe implant 2 is fully inserted in thesecond bone 62, the joint is fully closed.

FIG. 8A shows the hammertoe implant 2 as it is inserted in the secondbone 62. FIG. 8B illustrates the hammertoe implant 2 fully inserted intothe second bone 62. The first bone 60 and the second bone 62 are alignedand the joint therebetween is closed, forcing the expandable section 10into the reverse countersink 66 formed in the second bone 62. As shownin FIG. 8B, the expandable arms 10 a-10 d expand to a deployed positionwhen inserted fully into the reverse countersink 66. The expandable arms10 a-10 d have a deployed diameter sufficient to expand beyond the canal65 and to engage with a bearing surface 67 of the reverse countersink66. The reverse countersink 66 is sized such that the expandable section10 fits within the reverse countersink with minimal or no additionalspace to maintain the hammertoe implant 2 in a fixed position. In someembodiments, the expandable arms 10 a-10 d comprise an expanded diameterequal to the diameter of the reverse countersink 66. In someembodiments, the expandable arms 10 a-10 d are biased to a diametergreater than the diameter of the reverse countersink 66, allowing theexpandable arms 10 a-10 d to contact the inner sidewalls 69 of thereverse countersink 66.

FIG. 9 illustrates an isolated view of the expandable section 10inserted into the reverse countersink 66. As shown, the expandable arms10 a-10 d expand to a diameter that is substantially equal to thediameter of the reverse countersink 66. In some embodiments, theexpandable arms 10 a-10 d are biased to a diameter greater than thediameter of the cavity 66 to ensure the expandable arms 10 a-10 d expandto the full diameter of the countersink 66. The reverse countersink 66is sized and configured to receive the expandable section 10 withminimal extra space to prevent movement of the hammertoe implant 2 afterinstallation. Although the reverse countersink 66 is shown as a conicalcavity, the reverse countersink 66 may comprise any suitable shapecorresponding to the shape of the expandable section 10 in an expandedconfiguration.

With reference to FIGS. 6-9 and 20, a method 600 for coupling a firstbone 60 and a second bone 62 is discussed. In a first step 602, a canal68 is formed in the first bone 60. The canal 68 is sized and configuredto receive a first end 4 of an hammertoe implant 2. In a second step604, a canal 65 is formed in the second bone 62. The canal 65 in thesecond bone 62 is sized and configured to receive an instrument 50therein. The instrument 50 is configured to form a reverse countersink66 in the second bone 62. The canal 68 in the first bone 60 and/or thecanal 65 in the second bone 62 may be formed using, for example, ak-wire, a drill and/or any other suitable device. In some embodiments,the first bone 60 comprises a proximal phalanx, the second bone 62comprises a middle phalanx.

In a third step 606, the instrument 50 is inserted into the canal 65formed in the second bone 62. The instrument 50 comprises an instrumenttip 52 and a shaft 54. The instrument 50 is inserted to a firstpredetermined depth in the canal 65. In some embodiments, the instrument50 is inserted until the instrument tip 52 contacts a closed end of thecanal. In other embodiments, the instrument tip 52 is inserted to afirst predetermined depth indicated on the instrument 52. A deployablecutting edge 56 is coupled to the shaft 54. The instrument tip 52 andthe shaft 54 are configured to locate the cutting edge 56 at a secondpredetermined depth within the canal 65. In a fourth step 608, thecutting edge 56 is deployed and the instrument 50 is rotated about acentral axis to form a reverse countersink 66 within the second boneduring a fourth step 608. After forming the reverse countersink 66, thecutting edge 56 is collapsed against the shaft 54 and, in a fifth step610, the instrument 50 is removed from the canal 65.

In a sixth step 612, a sleeve (see FIG. 18) is placed over an expandablesection 10 of a hammertoe implant 2. The sleeve is configured tocompress the expandable section 10 and to provide a handle for rotatingthe hammertoe implant 2. In some embodiments, the sixth step 612 isomitted. In a seventh step 614, the first end 4 of the hammertoe implant2 is inserted into the canal 68 formed in the first bone 60. Thehammertoe implant 2 may be inserted by, for example, rotatablyinterfacing the threaded section 12 with the canal 68. The hammertoeimplant 2 is inserted to a predetermined depth in the first bone 60. Thepredetermined depth may correspond to a length of the threaded section12. In some embodiments, the threaded section 12 is configured to extendsubstantially through the entire width of the first bone 60. In someembodiments, a portion of the shaft 6 is inserted into the canal 68.

After the first end 4 is inserted into the first bone 60, the second end4 of the hammertoe implant 2 is inserted into the second bone 62 duringan eighth step 616. If a sleeve was disposed over the expandable section10 to maintain the expandable arms 10 a-10 d in a collapsed position,the sleeve is removed prior to insertion of the second end 4 into thesecond bone. In some embodiments, the expandable arms 10 a-10 d arebiased to an expanded position.

The expandable section 10 is inserted into the canal 65 formed in thesecond bone 62. The canal 65 exerts a force on the expandable arms 10a-10 d and forces the expandable arms 10 a-10 d into a collapsedposition. In the collapsed position, the expandable section 10 is sizedand configured to fit through the canal 65. For example, in someembodiments, the expandable arms 10 a-10 d have a diameter in acollapsed position equal to or less than an internal diameter of thecanal 65. The expandable section 10 is inserted through the canal 65 tothe reverse countersink 66 formed in the second bone 62. In a ninth step618, the expandable arms 10 a-10 d assume an expanded configuration, asshown in FIGS. 8-9. The expandable arms 10 a-10 d interface with abearing surface of the reverse countersink 66 formed in the second bone62. In some embodiments, the reverse countersink 66 and the expandablesection 10 of the hammertoe implant 2 are sized and configured toprevent movement of the hammertoe implant 2 after insertion of theexpandable head 10 into the reverse countersink 66.

FIGS. 10-16 illustrate additional embodiments of implants for joining afirst bone 60 and a second bone 62. FIGS. 10 and 11 illustrate oneembodiment of an implant 102 comprising an expandable section 110 havinga first expandable arm 110 a and a second expandable arm 110 b. In otheraspects, the implant 102 is similar to the hammertoe implant 2 describedin conjunction with FIGS. 1-9. The implant 102 is configured to couple afirst bone 60 and a second bone 62, for example, a proximal phalanx anda middle phalanx. FIG. 10 illustrates one embodiment of an implant 102having a square shaft 106 a. FIG. 11 illustrates one embodiment of animplant 102 having a cylindrical shaft 106 b. Those skilled in the artwill recognize that the shaft 106 may comprise any suitablecross-sectional shape.

FIGS. 12-16 illustrate embodiments of hammertoe implants 202, 302comprising a first expandable section 204 a, 304 a and a secondexpandable section 204 b, 304 b coupled by a shaft 206, 306. FIGS. 12-14illustrate one embodiment of an implant 202 having a first expandablesection 204 a and a second expandable section 204 b coupled by a squareshaft 206. Each of the first and second expandable sections 204 a, 204 bcomprise a plurality of expandable arms 210 a-210 d, 214 a-214 d. Theexpandable arms 210 a-210 d, 214 a-214 d are illustrated in a collapsedposition in FIGS. 12 and 13. FIG. 14 illustrates the expandable arms 210a-210 d, 214 a-214 d in an expanded position. The expandable sections204 a, 204 b are similar to the expandable section 10 discussed withrespect to FIGS. 1-9. FIGS. 15 and 16 illustrate one embodiment of animplant 302 comprising a first expandable section 304 a and a secondexpandable section 304 b coupled by a cylindrical shaft 306. Each of theexpandable sections 304 a, 304 b comprise a plurality of expandable arms310 a-310 d, 314 a-314 d.

The implants 202, 302 are configured to join a first bone to a secondbone, such as, for example, a middle phalanx to a proximal phalanx. FIG.17 illustrates one embodiment of the implant 302 coupling a first bone360 and a second bone 364. Canals 365 a, 365 b comprising reversecountersinks 366 a, 366 b are formed in each of the first bone 360 andthe second bone 362. The reverse countersinks 366 a, 366 b may be formedby, for example, the instrument 50 described in conjunction with FIGS.4-6. The first end 304 a of the implant 302 is inserted into the canal365 a of the first bone 360 in a collapsed state. In some embodiments,the canal 365 a exerts a force on the expandable arms 310 a-310 d,maintaining the expandable arms 310 a-310 d in a collapsed positionsized and configured to slideably transition through the canal 365 a.When the expandable section 304 a reaches the reverse countersink 366 a,the expandable arms 310 a-310 d expand and engage a bearing surface ofthe reverse countersink 366 a to maintain the implant 302 in the firstbone 360.

The second expandable section 304 b of the implant 302 is inserted intothe canal 365 b formed in the second bone 362. The canal 365 b comprisesa reverse countersink 366 b. The second end 304 b of the implant 302 isinserted into the canal 365 b of the second bone 362 in a collapsedstate. In some embodiments, the canal 365 b forces the expandable arms314 a-314 d into a collapsed state during insertion of the implant 302to allow the second end 304 b to traverse the canal 365 b. When thesecond expandable section 304 b reaches the reverse countersink 366 b,the expandable arms 314 a-314 d expand to a deployed position and engagea bearing surface of the reverse countersink 366 b. The first bone 360and the second bone 362 are aligned and maintained by the implant 302.

With reference to FIGS. 12-17 and 21, a method 650 for coupling a firstbone 60 and a second bone 62 is discussed. In a first step 652, a canal68 is formed in the first bone 60. In a second step 654, a canal 65 isformed in the second bone 62. The canals 65 and 68 are sized andconfigured to receive an instrument 50 therein. The instrument 50 isconfigured to form a reverse countersink 66 in each of the first bone 60and the second bone 62. The canal 68 in the first bone 60 and/or thecanal 65 in the second bone 62 may be formed using, for example, ak-wire, a drill and/or any other suitable device. In some embodiments,the first bone 60 comprises a proximal phalanx, the second bone 62comprises a middle phalanx.

In a third step 656, the instrument 50 is inserted into the canal 65formed in the second bone 62. The instrument 50 comprises an instrumenttip 52 and a shaft 54. The instrument 50 is inserted to a firstpredetermined depth in the canal 65. In some embodiments, the instrument50 is inserted until the instrument tip 52 contacts a closed end of thecanal. In other embodiments, the instrument tip 52 is inserted to afirst predetermined depth indicated on the instrument 52. A deployablecutting edge 56 is coupled to the shaft 54. The instrument tip 52 andthe shaft 54 are configured to locate the cutting edge 56 at a secondpredetermined depth within the canal 65. In a fourth step 658, thecutting edge 56 is deployed and the instrument 50 is rotated about acentral axis to form a reverse countersink 66 within the second boneduring a fourth step 608. After forming the reverse countersink 66, thecutting edge 56 is collapsed against the shaft 54 and, in a fifth step660, the instrument 50 is removed from the canal 65. In a sixth step662, the instrument is inserted into the canal 68 formed in the firstbone 60, the deployable cutting edge 56 is deployed, and a reversecountersink is formed in the first bone 60. The deployable cutting edge56 is collapsed against the shaft 54 after forming the reversecountersink in the first bone and the instrument 50 is removed from thefirst bone 60.

In a seventh step 664, a sleeve (see FIG. 18) is placed over the secondexpandable section 214 of a hammertoe implant 202. The sleeve isconfigured to compress the second expandable section 214 and to providea handle for gripping the hammertoe implant 2. In some embodiments, thesixth step 612 is omitted. In an eighth step 666, the first expandableend 210 of the hammertoe implant 2 is inserted into the canal 68 formedin the first bone 60. The canal 68 exerts a force on the expandable arms210 a-210 d and forces the expandable arms 210 a-210 d into a collapsedposition. In the collapsed position, the expandable section 210 is sizedand configured to fit through the canal 68. For example, in someembodiments, the expandable arms 210 a-210 d have a diameter in acollapsed position equal to or less than an internal diameter of thecanal 68. The expandable section 210 is inserted through the canal 68 tothe reverse countersink formed in the first bone 60. In a ninth step668, the expandable arms 210 a-210 d assume an expanded configuration.The expandable arms 210 a-210 d interface with a bearing surface of thereverse countersink formed in the first bone 60. In some embodiments,the reverse countersink and the expandable section 210 of the hammertoeimplant 202 are sized and configured to prevent movement of thehammertoe implant 202 after insertion of the expandable head 210 intothe reverse countersink.

After the first expandable section 210 is inserted into the first bone60, the second expandable section 214 of the hammertoe implant 202 isinserted into the second bone 62 during a tenth step 670. If a sleevewas disposed over the expandable section 214 to maintain the expandablearms 214 a-214 d in a collapsed position, the sleeve is removed prior toinsertion. In some embodiments, the expandable arms 214 a-214 d arebiased to an expanded position.

The second expandable section 214 is inserted into the canal 65 formedin the second bone 62. The canal 65 exerts a force on the expandablearms 214 a-214 d and forces the expandable arms 214 a-214 d into acollapsed position. In the collapsed position, the second expandablesection 214 is sized and configured to fit through the canal 65. Forexample, in some embodiments, the expandable arms 214 a-214 d have adiameter in a collapsed position equal to or less than an internaldiameter of the canal 65. The second expandable section 214 is insertedthrough the canal 65 to the reverse countersink 66 formed in the secondbone 62. In an eleventh step 672, the expandable arms 214 a-214 d assumean expanded configuration. The expandable arms 214 a-214 d interfacewith a bearing surface of the reverse countersink 66 formed in thesecond bone 62. In some embodiments, the reverse countersink 66 and thesecond expandable section 214 of the hammertoe implant 202 are sized andconfigured to prevent movement of the hammertoe implant 202 afterinsertion of the second expandable section 214 into the reversecountersink 66.

FIG. 18 illustrates one embodiment of a combination sleeve and driverconfigured to insert one or more embodiments of the hammertoe implant.For example, in some embodiments, the combination sleeve and driver 400is configured for use with the hammertoe implants 2, 102, 202, 302illustrated in FIGS. 1-17. The combination sleeve and driver 400comprises a longitudinal sleeve 402 defining a channel 404 configured toreceive an expandable section 10 of an implant 2. The expandablefeatures 10 a-10 d of the expandable section 10 are compressed againstthe implant 2 by the channel 404 and maintained in a collapsed position.The combination sleeve and driver 400 comprises a driver head 406. Thedriver head 406 may comprise a quick connect feature 408 configured toattach the combination sleeve and driver 400 to a handle to drive theimplant 2. The quick connect feature 408 and the handle may beconfigured to provide translation, rotation, and/or any other suitablemovement to couple the first end 4 to the first bone. In someembodiments, the internal mating features of the channel 404 providerotational control such that the implant 2 can be driver proximally orbacked out distally. For example, in one embodiment, the expandablefeatures 10 a-10 d and the channel 404 operate as an inverted Phillipshead interface. FIG. 19 illustrates an alternative embodiment of acombination sleeve and driver 500. In the embodiment of FIG. 19, thechannel 504 comprises a wider opening and rounded edges to accommodatethe expandable features 10 a-10 d of the expandable side 10.

In some embodiments, a bone implant is disclosed. The bone implantcomprises a first end configured to couple to a first bone, a second enddefining a first expandable section comprising at least one expandablefeature, and an elongate shaft extending longitudinally between thefirst end and the second end. The first expandable section is sized andconfigured to be received within a reverse countersink formed in asecond bone in a collapsed state. The first expandable section expandswithin the reverse countersink such that the at least one expandablefeature couples to a bearing surface of the reverse countersink.

In some embodiments, the first expandable section comprises a pluralityof expandable arms.

In some embodiments, the expandable section comprises four expandablearms.

In some embodiments, the first end comprises a threaded section.

In some embodiments, the threaded section comprises a length sufficientto extend through a thickness of the first bone.

In some embodiments, the first end defines a second expandable sectioncomprising at least one expandable feature. The second expandablesection is configured to be received within a reverse countersink formedin the first bone in a collapsed state. The second expandable sectionexpands within the reverse countersink such that the at least oneexpandable feature couples to a bearing surface of the reversecountersink.

In some embodiments, the second expandable section comprises a pluralityof expandable arms.

In some embodiments, the first expandable section comprises a materialselected from the group consisting of: Nitnol, titanium, alloy, andstainless steel.

In some embodiments, the first bone comprises a proximal phalanx and thesecond bone comprises a middle phalanx.

In some embodiments, the elongate shaft extends a predetermined lengthsuch that when the first end is fully inserted into the first bone andthe second end is fully inserted into the second bone there issubstantially no gap between the first and second bones.

In some embodiments, a surgical tool is disclosed. The surgical toolcomprises a shaft sized and configured to be received within a canalformed in a bone and at least one expandable cutting edge formedintegrally with the shaft. The expandable cutting edge comprises acollapsed position configured for insertion into the canal and anexpanded position configured to form a reverse countersink in the canal.The expandable cutting edge is deployed to the expanded position afterbeing inserted into the canal.

In some embodiments, the surgical tool comprises a conical headconfigured to contact an end of the canal and to space the expandablecutting edge a predetermined distance from the end of the canal.

In some embodiments, the at least one expandable cutting edge isdeployed by mechanical deflection.

In some embodiments, the at least one expandable cutting edge comprisesa hinge.

In some embodiments, the at least one expandable cutting edge isconfigured to form the reverse countersink when the shaft is rotated.

In some embodiments, a method for correcting hammertoe is disclosed. Themethod comprises the steps of forming a first canal in a first bone,forming a second canal in a second bone, inserting a surgical instrumentinto the second canal, and rotating the surgical tool to form a reversecountersink in the second canal of the second bone. The surgicalinstrument comprises a shaft, a head located at a first end of theshaft, and an expandable cutting edge formed integrally with the shaftand deployable from a collapsed position to an expanded position.

In some embodiments, the method further comprises inserting a first endof an implant into the first canal in the first bone.

In some embodiments, the method further comprises inserting an secondend of an implant into the second canal in the second bone. The secondend of the implant comprises an expandable section wherein theexpandable section comprises at least one expandable feature. Theexpandable section is inserted through the second canal to the reversecountersink in a collapsed position. The at least one expandable featureexpands within the reverse countersink such that the at least oneexpandable feature couples to a bearing surface of the reversecountersink.

In some embodiments, the canal exerts a force on the expandable sectionto maintain the expandable section in a collapsed state duringinsertion. The at least one expandable feature deploys when fullyinserted into the reverse countersink.

In some embodiments, the first end of the implant comprises a threadedsection. Inserting the first end of the implant comprises rotating thethreaded section into engagement with the first canal.

In some embodiments, a method for correcting hammertoe is disclosed. Themethod comprises the steps of forming a first canal in a first bone,forming a second canal in a second bone, and inserting a surgicalinstrument into the first canal. The surgical instrument comprises ashaft, a head located at a first end of the shaft, and an expandablecutting edge formed integrally with the shaft and deployable from acollapsed position to an expanded position. The method further comprisesrotating the surgical tool to form a reverse countersink in the firstcanal of the first bone, inserting the surgical instrument into thesecond canal, and rotating the surgical tool to form a reversecountersink in the second canal of the second bone.

In some embodiments, the method further comprises inserting a first endof an implant into the first canal in the first bone. The first end ofthe implant comprising a first expandable section having at least oneexpandable feature. The first expandable section is inserted through thefirst canal to the reverse countersink in a collapsed position. The atleast one expandable feature expands within the reverse countersink suchthat the at least one expandable feature couples to a bearing surface ofthe reverse countersink.

In some embodiments, the first canal exerts a force on the firstexpandable section to maintain the first expandable section in acollapsed state during insertion. The at least one expandable featuredeploys when fully inserted into the reverse countersink.

In some embodiments, the method further comprises inserting a second endof the implant into the second canal in the second bone. The second endof the implant comprises a second expandable section having at least oneexpandable feature. The second expandable section is inserted throughthe second canal to the reverse countersink in a collapsed position. Theat least one expandable feature expands within the reverse countersinksuch that the at least one expandable feature couples to a bearingsurface of the reverse countersink.

In some embodiments, the second canal exerts a force on the secondexpandable section to maintain the second expandable section in acollapsed state during insertion. The at least one expandable featuredeploys when fully inserted into the reverse countersink.

Although the subject matter has been described in terms of exemplaryembodiments, it is not limited thereto. Rather, the appended claimsshould be construed broadly, to include other variants and embodiments,which may be made by those skilled in the art.

What is claimed is:
 1. A method for correcting hammertoe, comprising thesteps of: forming a first canal in a first bone; forming a second canalin a second bone; providing a surgical tool comprising: a shaft sizedand configured to be received within a canal formed in a bone, the shafthaving a conical head and defining a longitudinal axis; and a cuttingedge having a distal end and a proximal end, the distal end being in afixed position with respect to the shaft and the proximal end of thecutting edge movable from a first position to a second position, whereinthe radial distance from the longitudinal axis to the proximal end ofthe cutting edge in the first position is less than the radial distancefrom the longitudinal axis to the proximal end of the cutting edge inthe second position inserting said surgical tool into the second canal;rotating said surgical tool to form a reverse countersink in the secondcanal of the second bone; inserting a first end of an implant into thefirst canal in the first bone; inserting a second end of the implantinto the second canal in the second bone, the second end including aplurality of expandable arms each having a connection end and a freeend, wherein the plurality of expandable arms are inserted through thesecond canal in a collapsed state, and wherein the plurality ofexpandable arms expand to an expanded state in which the free ends ofthe plurality of expandable arms contact a bearing surface of thereverse countersink.
 2. The method of claim 1, wherein the reversecountersink has a sidewall, and wherein when the second end of theimplant is fully inserted into the second canal the free ends of theplurality of expandable arms contact the sidewall.
 3. The method ofclaim 1, wherein the second canal exerts a force on the plurality ofexpandable arms to maintain the plurality of expandable arms in thecollapsed state during insertion.
 4. The method of claim 1, wherein thefirst end of the implant comprises a threaded section, and whereininserting the first end of the implant comprises rotating the threadedsection into engagement with the first canal.
 5. The method of claim 1,further comprising rotating said surgical tool to form a second reversecountersink in the first canal of the first bone; wherein the first endof the implant includes a second plurality of expandable arms eachhaving a connection end and a free end, wherein the second plurality ofexpandable arms are inserted through the first canal in a collapsedstate, and wherein the second plurality of expandable arms expand to anexpanded state in which the free ends of the second plurality ofexpandable arms contact a bearing surface of the second reversecountersink.
 6. The method of claim 5, wherein the first canal exerts aforce on the second plurality of expandable arms to maintain the secondplurality of expandable arms in a collapsed state during insertion, andwherein the second plurality of expandable arms deploy when fullyinserted into the first canal.